Engine piston



Feb. 2, 1937. R. SCHNEIDER ENGINE PISTON Filed July 15, 195o 1 f,lllllflllx u nlmlll 9 Patented Feb.' 2, 1937 UNITED STATES PATENToFF'Ic-E 2,069,594 ENGINE PIs'roN Rudolph schneider', st. Louis, Mo.,asngnor to Busch-Sulzer BrosfDiesel Engine Company, St. Louis, Mo., acorporation of Missouri Application July 15, 1930, Serial No. 468,079

2 Claims.

In the accompanying drawing, Fig. 1 is an axial section, through thepiston pin axis, of a trunk piston incorporating one form oi theinvention.

Fig. 2 Ia similar section on line II-II f Fig. 3. Fig. 3 is acrosssection of the piston at the piston pin axis. I

'I'he piston head, marked I in Figs. 1 and 2, is made hollow and itsinterior chamber forms part of the circuit of a cooling liquid system,presently referred to; its exterior cylindrical wall carries the usualpiston rings. The piston trunk or skirt 2 is separately made, in thepresent case, and rigidly secured to the piston head but 'it could bemade in one piece with the head i! desired, and vas will later appear..The connecting rod 3 is connected to the piston by means of anintermediate'structure, herein f or convenience termed a 4false trunk,and indicated in its several parts by the reference numerals 4, I, 6, 1,l, I4 and I5. This structure is shaped to it the piston proper at ornear its head part and also at an intermediate point of the piston trunkand has a continuous circular contact therewith at each point, viz. atits top shoulder 5', where, in the present case, it clamps thetopilangeoi the-trunk 2' against the bottom flange of the piston head I.and atvits upper cylindricalcorner 6, where it bears on thecorresponding cylindrical surface at the top part of the'trunk 2, andiinally, at its lower cylindrical surface 1 where it bears against bolts9 in -diametrlcally `opposite positions,n as.

shown In Fig. a, and by two threaded nippIes In, also diametricallylocated, which serve both as bolts and as ducts for conducting thecooling liquid to and from the piston head chamber.' Both the b olts 9and the nipples I0 are threaded into 'the base of the piston head andextend irom'top pressure 'on the piston pin, which of course is 55 tobottom of the false trunk, their heads or nuts thus being low downandnear to the open end of the trunk and hence easily accessible. The lowerends of the nipples I0 will be understood to be designed for appropriateconnection with 4the 5 fixed parts of the piston cooling system.

The. piston pin is held in a bearingbox 4 iny the false trunk, which inthe present case is a crossbore' through the structure of the falsetrunk,

lined with a bearing bushing I2. -The pin rotates l0 relatively to thecross bore and bushinginstead of being fast to the piston according toconventional engine design. The connecting red is connected to the pinby means of its head ange 3a,

which is rbated into a. recess cut in the lower side l5 of the pistonpin, midway of its ends, and bolted thereto by the four bolts I3. 'I'hebushing I2 and the lower part of the integral false trunk structure arecutaway to accommodate this connection. Except for' the recess whichaccommodates 20 the diameter of the piston and helclagainstend- A 25wise displacement in the cross bore by the connecting rod. The recessedface by which it is attached to the connecting rod is within thecylindrical contour of the pin so that the pin may be readily producedby simple manufacturing proc-30 endwise into-the esses and can also beinserted cross-bore.

As will be observed from the drawing, the false trunk structure is ofskeletonized internal construction being made strong by its internalstrut 35 webs I4, which converge downwardly from the annular shoulder 5to the bearing box 4 and by the tubularcasings I 5 through which the'bolt members 9 and I0 are passed. f

f In the assembly oi the pms, the bushing I2, 40

when one isemployed, is introduced into' the box 4 of the false trunkand desirably keyed to it by the keys I6 and the keys are locked by setscrews I1, thus to guard vagainst any movement of the bushing, rotary orendwise, in the piston structure. The piston pin II is next introduced,being inserted endwise into the bushing andthe connecting rod is thenadjusted to the piston pin re- 1cess and bolted therein. vThe false'trunk with these parts connected toit then receives the real 5 trunk 2over it and the piston head I on top of that and the bolt members 9 andIB-are then inserted and set up, thus completing the operation. By theconstruction described the downward the maximum in an internalcombustion engine, is taken over the whole top surface of the pistonpin, from end to end thereof, being thus of the maximum possible area.Such pressure is symmetrically transmitted to the pin from the annularshoulder 5 through the internal strut mem-I bers already referred to.'I'he area of bearing contact of the cross bore or bushing upon theunderside of thev piston pin is reduced by the cut-out for theconnecting rod connection, but this is notl objectionable as the maximumpressure on this surface is only that due to the inertia of the pistonat topldead center and therefore small as compared to 'the combustionpressure on the top. It is adequately taken by the end pory tions of thepin at either side of the connecting rod joint which portions aresymmetrical and of equal lengtn and area and of` equal bearing contacton the box or on the bearing bushing therein, so that there is notendency for the bearing to wear more at one end than at the other whichwould skew the pin in the piston and set up lateral strains in theconnecting rod, such strains being particularly objectionable incombustion engines because of the sudden pressures to which suchapparatus is subjected. Moreover, the piston pin being retained againstdisplacement by virtue of its connection to the connecting rod, as abovestated, is also free to adjust itself longitudinally within the limitsof the cut-out portion of the cross bore, which is an important featurein that-it not only makes Afor symmetry of pressure transmission andequality of piston pin wear but in thatiit also relieves the other partsor any straineincident to the change of length of the piston pinfrom'thermal causes and also of such distortion as occurs or islikely'to occur in other .types of pistons from such causes or theoperation of pressing the pin into the piston walls.

'I'he piston pin bearing is lubricated by oil grooves as usual, suppliedthrough the connecting rod bore I8 and the oil used for this purpose iseffectively kept out of the combustion space,

since it is confined within the trunk 2.`

I claim:

1. A combustion enginepiston comprising a head, .a separately formedtrunk, a false trunk, and bolt means for attaching fthe trunk to thehead and the false trunk to both of said parts,

said false trunk having an annular bearing near its lower end upon theinner surface of the real j trunk and formed with a bearing box andhaving a. cylindrical piston-pin in said box, said box providing asubstantially continuous bearing surface for the piston-pin against itstop side and a

